Engine starter gearing



Dec. 14, 1965 J. J. DIGBY 3,222,938

ENGINE STARTER.GEARING Filed. Jan. 8, 1964 2 Sheets-Sheet 1 INVENTOR. James 1 4 Wl TNESS:

2m wkm W AT T GENE Y Dec. 14, 1965 J. J. DIGBY 3,222,938

ENG INE S TAR'I'ER GEAR ING Filed Jan. 8, 1964 2 Sheets-Sheet 2 INVENTOR.

WITNESS: BY James jo /7% 5m. 522M;

United States Patent Oflice 3,222,938 Patented Dec. 14, 1965 3,222,938 ENGINE STARTER GEARING James J. Digby, Elmira, N .Y., assignor to The Bendix Corporation, Elmira, N.Y. Filed Jan. 8, 1964, Ser. No. 336,544 4 Claims. (Cl. 74-7) The present invention relates to engine starter gearing and more particularly to a starter drive of the type in which a drive pinion is caused to engage and drive an engine gear responsive to acceleration of the starting motor shaft, and to disengage therefrom responsive to acceleration of the engine gear when the engine becomes self-operating.

It is an object of the present invention to provide a novel engine starter drive of the above type which is eflicient and reliable in operation and simple and economical in construction.

It is another object to provide such a device which is self-contained as a unit saleable as an article of commerce, needing only to be slipped on the armature shaft of the starting motor and anchored thereon to be fully operative for its intended service.

It is another object to provide such a device which is of very short overall length as compared to previous forms of drive of comparable load capacity.

It is another object to provide such a device which re quires no special tools or technique to mount the unit on the starting motor shaft or to dismount it therefrom.

It is another object to provide such a device in which a common means is provided for holding the pinion in mesh with the engine gear until the engine is reliably self-operative, and for thereafter preventing the pinion from drifting into undesired contact with the engine gear during operation of the engine.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing, in which:

FIGURE 1 is a side elevation, partly broken away and in section of a preferred embodiment of the invention shown as mounted on the armature shaft of a starting motor, not illustrated, the parts being shown in normal or idle position;

FIGURE 2 is a similar view showing the parts in operative position;

FIGURE 3 is a similar view showing the parts in the positions assumed during initial firing of the engine; and

FIGURE 4 is a detail of the screw shaft showing the abutment for engaging the latch in order to prevent the pinion from being demeshed until the engine has become reliably self-operative.

In FIGURE 1 of the drawing there is illustrated a power shaft 1 having a reduced portion 2 which is externally splined, forming a shoulder 3, and a further reduced portion 4 which terminates in a bearing portion 5 which is arranged to be mounted in an outboard hearing attached to or rigid with the frame of the starting motor, not illustrated, in the usual manner.

A driving sleeve 6 having interior splines 7 slidably fitting the splined portion 2 of the power shaft is mounted thereon and is maintained in position abutting the shoulder 3 on the power shaft by means of a pin 8 which traverses the sleeve and enters a pilot socket 9 in the power shaft 1.

A driving clutch ring 11 is splined on the exterior of the driving sleeve 6 and is provided on one end with overrunning clutch teeth 12 adapted to cooperate with similar teeth 13 on the adjacent end of a hollow screw shaft 14 which is slidably journaled on the driving sleeve 6. A spring snap ring 15 is located in a circumferential groove in the driving sleeve 6 to form an abutment which defines the normal or idle position of the driving clutch member 11 and screw shaft 14. A coiled compression spring 16 is located in a counterbore 17 in the end of the screw shaft 14, bearing at one end against the bottom 18 of the counterbore and at its other end against a thrust washer 20 which is seated against a split spring ring 19 mounted in a groove in the forward end of the driving sleeve 6. Spring 16 serves to yieldingly maintain the clutch teeth 13 of the screw shaft in contact with teeth 12 of the driving clutch member 11.

Hereafter, as used in the specification, the term forward and rearward are intended to refer to the direction of operation of the movable parts of the device, forward being in reference to the movement of the pinion and its associated parts into mesh with the engine gear, and rearward referring to its retracting movement to idle position.

A control nut 21 is threaded on the screw shaft 14 and is rigidly connected by means of a barrel member 22 with a pinion 23 which is slidably journaled on the reduced portion 4 of the driving shaft 1 in position to be moved into and out of mesh with a gear 24 on the engine to be started. The operative position of the pinion 23 is defined by means of an abutment member 25 which is located on the driving shaft 1 by means of a thrust ring 26 and a retaining ring 27.

As best shown in FIGURE 4 the screw shaft 14 is notched as shown at 30 to form a radial abutment 28 adjacent its forward end and is beveled off at its rear end as indicated at 29 to form a frusto-conical surface. A detent and latch member 31 is mounted for radial sliding movement in a radial passage in the control nut 21, and is pressed inwardly by means of a spring 32 retained by a cap 33 fixedly mounted in, and closing the radial passage of the control nut. When the parts are in idle position as shown in FIGURE 1, the detent member 31 rests on the frusto-conical surface 29 at the rear end of the screw shaft 14 and thereby yieldingly resists the movement of the control nut and pinion assembly toward meshing position. When the parts are in operative position, as shown in FIGURE 2, the latch member 31 is seated in the notch 30, spaced from the abutment 28 as shown in dotted lines in FIGURE 4. It is thus in posi tion to engage the abutment 28 on the screw shaft and prevent demeshing movement of the control nut and pinion assembly until the rotary speed of the parts is sufficiently high to withdraw the latch 31 by centrifugal force against the pressure of the spring 32. The threads at the forward end of the screw shaft are preferably of slightly reduced depth, and the threads at the forward end of the control nut are slightly counterbored, to prevent the control nut from falling olf the screw shaft during handling and assembly.

Means are provided for yieldingly resisting rearward movement of the driving clutch member 11 away from its normal position. As here shown, this means com prises an annular disc 34 slidably mounted on the driving sleeve 6 in abutting relation to the driving clutch ring 11, a cup member 35 surrounding the disc 34, and a meshenforcing spring 36, and a cushioning ring 37 of elastically deformable material both housed within the cup 35 between the disc 34 and the bottom flange 38 of said cup. The driving sleeve 6 has a radial shoulder 39 at its rearward end which forms an abutment for the bottom flange 38 of the cup 35.

The mesh-enforcing spring 36 occupies the space between the disc 34 and the bottom flange 38 of the cup member so as to normally maintain the driving clutch ring 11 pressed against the thrust ring 15 on the driving sleeve 6. The cushioning ring 37 rests against the bottom flange 38 of the cup but is spaced from the disc 34 so as to permit a predetermined compression of the meshenforcing spring 36 to take place before the disc 34 is brought into engagement with the cushioning member.

The locating pin 8 has a flattened stem 41 extending radially from the driving sleeve 6 providing a shoulder 42 which is substantially flush with the exterior surface of said sleeve. The bottom flange 38 of the cup member 35 is normally seated against the flat surface of the locating pin and engages the shoulder 42 to thereby retain the locating pin in operative position. However, in order to insert or remove the locating pin, it is only necessary to move the cup 35 forwardly by compressing the mesh-enforcing spring 36, the space 43 between the disc 34 and the cushioning member 37 being sufficient to allow such movement without compressing the cushioning member.

In operation, starting with the parts in the position illustrated in FIGURE 1, acceleration of the drive shaft 1 in the direction of the arrow A, causes the control nut 21 to thread itself onto the screw shaft 14, overcoming the initial retardation of the detent 31 and moving the barrel assembly forwardly until the pinion 23 enters into mesh with the engine gear 24 and is stopped by the abutment 25. Further rotation of the drive shaft 1 and screw shaft 14 causes the latter to be traversed in the rearward direction by screw-jack action, compressing first the meshenforcing spring 36, and thereafter the cushioning ring 37 until suflicient torque has been built up to initiate the rotation of the engine gear. This rearward movement of the screw shaft 14 is permitted by a counter-bore 45 in its rearward end which accommodates the snap ring 15.

If, during the meshing operation, a tooth of the pinion 23 should come into abutment with a tooth of the engine gear 24, the meshing movement of the pinion assembly is arrested and the screw shaft 14 is caused to move rearwardly against the compression of the mesh-enforcing spring 36. When sufficienttorque has been built up due to the compression of the mesh-enforcing spring, the pinion is indexed into position for proper registry of its teeth with the tooth spaces of the engine gear and the spring 36 then expands and snaps the pinion into initial engagement with the engine gear, after which meshing and cranking take place in the usual manner.

When the fuel charges in one or more of the cylinders of the engine are ignited, the engine gear is accelerated, and the speed of rotation of the pinion is correspondingly increased. If the explosions in the engine cylinders are sufliciently powerful, the pinion barrel and control nut assembly will be accelerated more rapidly than the motor shaft. Since, at this time, the detent-latch 31 in the control nut 21 prevents the control nut from being threaded back to its idle position on the screw shaft 14 by engage ment of the latch with the abutment 28 on the screw shaft, the pinion is maintained in mesh with the engine gear, and the screw shaft is carried along with the pinion-barrel assembly, overrunning the driving clutch ring 11 as permitted by the ratcheting of the clutch teeth 12, 13, as shown in FIGURE 3. If the initial impulses of the engine cylinders should be irregular or ineffective to maintain the rotation of the engine crank shaft, as soon as the speed of rotation of the motor shaft equals that of the pinion-barrel assembly the clutch teeth 12, 13 re-engage and cranking of the engine by the starting motor is re sumed.

When the engine becomes reliably self-operative, the consequent speed of rotation of the pinion-barrel assembly becomes high enough to cause the detent-latch 31 to move outward by centrifugal force, disengaging itself from the abutment 28 on the screw shaft. The screw shaft is thus permitted to be decelerated to the concurrent speed of the motor shaft by virtue of its frictional connection to the driving clutch ring 11 and driving sleeve 6 made effective by the clutch spring 16. The control nut 21 with the associated barrel and pinion are consequently traversed back to idle position, where they are maintained by the engagement of the detent-latch 31 with the conical surface 29 of the screw shaft.

While one form of the invention has been shown and described in detail, it will be understood that changes may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an engine starter drive:

a power shaft having a shoulder formed thereon and a pilot hole adjacent said shoulder,

a driving sleeve splined on the power shaft,

a locating pin mounted in said sleeve and engaging in said pilot hole to maintain the sleeve in engagement with said shoulder,

a hollow screw shaft slidably journalled on the driving sleeve,

a driving clutch ring splined on the driving sleeve having an overrunning clutchconnection with said screw shaft,

means defining the normal engaged position of the screw shaft and the driving clutch ring,

yielding means urging the screw shaft toward its nor mal position,

yielding mesh-enforcing means including an enclosing cup member having a bottom flange slidably mount ed on the driving sleeve,

said yielding mesh-enforcing means resisting movement of the driving clutch member away from its normal position,

said locating pin having a flattened stem protruding radially from the driving sleeve and providing a shoulder substantially flush with the exterior surface of said sleeve,

said bottom flange of the cup member being normally seated against the flat surface of the locating pin and engaging said shoulder to thereby retain the locating pin in operative position,

cushioning means resisting further axial movement of the driving clutch member after a predetermined compression of the mesh-enforcing means,

a control nut threaded on said screw shaft,

a pinion slidably journalled on the power shaft for movement into and out of mesh with a gear of the engine to be started, and

a barrel member rigidly connecting the control nut and pinion.

2. An engine starter drive as set forth in claim 1 in which said mesh-enforcing means is in the form of a compression spring, and

the cushioning means is in the form of an annular elastic member surrounding said spring,

said cushioning means being so dimensioned as to permit the cup to be moved away from the pin sufiiciently to permit removal of the pin without the necessity of compressing the cushioning means.

3. In an engine starter drive:

a power shaft,

a driving sleeve fixedly mounted thereon,

a hollow screw shaft slidably journalled on the driving sleeve,

a driving clutch ring splined on the driving sleeve, having an overrunning clutch connection with said screw shaft,

means defining the normal engaged position of the screw shaft and the driving clutch ring,

yielding means urging the screw shaft toward its normal position,

yielding mesh-enforcing means resisting movement of the driving clutch member away from its normal position,

cushioning means resisting further axial movement of the driving clutch member after a predetermined compression of the mesh-enforcing means,

a control nut threaded on said screw shaft,

a pinion slidably journalled on the power shaft for movement into and out of mesh with a gear of the engine to be started,

a barrel member rigidly connecting the control nut and pinion,

said hollow screw shaft formed with a radial abutment adjacent its forward end, and is bevelled off at its rear end to form a frusto-conical surface, and

a spring-pressed detent and latch member slidably mounted in the control nut for engagement with the screw shaft and arranged to engage said frustoconical surface to resist movement of the control nut and pinion assembly away from its normal position and to engage said radial abutment to retain the pin ion in operative position.

4. In an engine starter drive:

a power shaft,

a driving sleeve fixedly mounted thereon,

a hollow screw shaft slidably journalled on the driving sleeve,

a driving clutch ring splined on the driving sleeve, having an overrunning clutch connection with said screw shaft,

means defining the normal engaged position of the screw shaft and the driving clutch ring,

yielding means urging the screw shaft toward its normal position,

yielding mesh-enforcing means resisting movement of the driving clutch member away from its normal position,

cushioning means resisting further axial movement of the driving clutch member after a predetermined compression of the mesh-enforcing means,

a control nut threaded on said screw shaft,

a pinion slidably journalled on the power shaft for movement into and out of mesh with a gear of the engine to be started,

a barrel member rigidly connecting the control nut and pinion,

the threads of the screw shaft adjacent its forward end are cut less deeply than on the rest of said shaft, and

the forward end of the control nut is counterbored slightly, so that the normal traverse of the control nut on the screw shaft is not restricted, but the control nut is prevented from running off the forward end of the screw shaft.

References Cited by the Examiner UNITED STATES PATENTS 2,327,852 8/1943 Batchelder 28752.08 2,704,458 3/ 1955 Spencer 74-7 2,907,214 10/1959 Hahn 74-6 2,933,926 4/1960 Buxton et a1. 747 2,984,115 5/1961 Digby 747 2,999,705 9/1961 Spencer 74-7 X MILTON KAUFMAN, Primary Examiner. 

1. IN AN ENGINE STARTER DRIVE: A POWER SHAFT HAVING A SHOULDER FORMED THEREIN AND A PILOT HOLE ADJACENT SAID SHOULDER, A DRIVING SLEEVE SPLINED ON THE POWER SHAFT, A LOCATING PIN MOUNTED IN SAID SLEEVE AND ENGAGING IN SAID PILOT HOLE TO MAINTAIN THE SLEEVE IN ENGAGEMENT WITH SAID SHOULDER, A HOLLOW SCREW SHAFT SLIDABLY JOURNALLED ON THE DRIVING SLEEVE, A DRIVING CLUTCH RING SPLINED ON THE DRIVING SLEEVE HAVING AN OVERRRUNNING CLUTCH CONNECTION WITH SAID SCREW SHAFT, MEANS DEFINING THE NORMAL ENGAGED POSITION OF THE SCREW SHAFT AND THE DRIVING CLUTCH RING, YIELDING MEANS URGING THE SCREW SHAFT TOWARD ITS NORMAL POSITION. YIELDING MESH-ENFORCING MEANS INCLUDING AN ENCLOSING CUP MEMBER HAVING A BOTTOM FLANGE SLIDABLY MOUNTED ON THE DRIVING SLEEVE, SAID YIELDING MESH-ENFORCING MEANS RESISTING MOVE- 